Accumulation
Use accumulation procedures for date-type columns to generate equally spaced time series data.
For the Exponential Smoothing algorithm, the accumulation procedure is
applied when the column is a date type (date
,
datetime
, timestamp
, timestamp with
timezone
, or timestamp with local timezone
). The case id
can be a NUMBER
column whose sort index represents the position of the
value in the time series sequence of values. The case id column can also be a date type.
A date type is accumulated in accordance with a user specified accumulation window.
Regardless of type, the case id is used to transform the column into an equally spaced
time series. No accumulation is applied for a case id of type NUMBER
.
As
an example, consider a time series about promotion events.
The time column contains the
date of each event, and the dates can be unequally spaced. The user must specify the
spacing interval, which is the spacing of the accumulated or transformed equally spaced
time series. In the example, if the user specifies the interval to be month, then an
equally spaced time series with profit for each calendar month is generated from the
original time series. Setting EXSM_INTERVAL
is used to specify the
spacing interval. The user must also specify a value for
EXSM_ACCUMULATE
, for example, EXSM_ACCU_MAX
, in
which case the equally spaced monthly series would contain the maximum profit over all
events that month as the observed time series value.